Bronchial asthma

Curated by Luigi Ferritto (1), Walter Ferritto (2), Giuseppe Fiorentino (3)

Generality

Bronchial asthma is one of the most frequent diseases and is characterized by a reversible bronchial obstruction.

The symptomatology includes:

cough
wheezing
shortness of breath
sense of constriction in the chest.

These symptoms are variable daily, but prevail at night and early morning.

Outline of Physiopathology

In the presence of asthma, at the bronchial level there is a hyperreactivity of the smooth muscle, regulated by the action of the parasympathetic nervous system through the vagus nerve.

During bronchial inflammation, mast cells, eosinophils and T lymphocytes release chemical mediators that act directly on: musculature, glands and capillaries.

During an asthmatic crisis, the inhaled air reaches the alveoli, but the presence of bronchial obstruction prevents it from escaping with exhalation. Thus, air can enter, but cannot escape from the alveoli.

Risk factors

The risk factors for asthma can be classified into:

genetic factors
environmental factors

The latter include all those factors that influence the development of asthma in predisposed individuals, and that cause exacerbations and / or persistent symptoms in subjects suffering from the disease itself.

Genetic factors that influence the development of asthma

Atopy is a genetically determined predisposition to produce an excess of IgE in response to exposure to allergens, and is evidenced by the demonstration of increased serum levels of specific IgE and / or with a positive response to skin allergy tests (prik test) carried out with a battery of standardized inhalant allergens.

The proportion of asthma attributable to atopy is about half of the cases.

Atopy presents a familiarity; therefore, there is an increased risk of developing asthma in the presence of atopic parents with asthma.

The manifestation of atopy has a natural history.

Atopic dermatitis usually precedes the development of allergic rhinitis and asthma. Allergic rhinitis is therefore an important risk factor for the development of asthma. Not by chance, often the two pathologies coexist in the same patient and in many cases allergic rhinitis precedes the development of asthma. Another element to consider is the possible presence of wheezing (hiss that characterizes the breath of the newborn) recurrent in the first years of life. Some of these children will develop asthma.

Environmental factors that influence the development of bronchial asthma

Allergens are considered an important cause of bronchial asthma. The increased incidence of asthma mainly concerns the perennial forms, in a considerable part of which it is possible to highlight a sensitization to indoor allergens, such as mites, derivatives of domestic animals (cat and dog) and molds.

A meta-analysis on environmental factors considered to be responsible for the incidence and severity of asthma concluded that exposure to indoor allergens is the environmental factor with the strongest effect on the development of asthma.

The main allergenic sources of outdoor environments are pollens, derived from herbaceous and arboreal plants and mycophytes. Other agents responsible for asthma are professional sensitizers. These are responsible for 9 - 15% of asthma cases in adults. The most frequently involved substances are isocyanates, flour, cereal powder and wood and latex.

Tobacco smoking plays an important role in the development of asthma and negatively affects disease control. Exposure to passive smoking, either pre-natal for the mother's smoking habit during pregnancy, or during childhood, is an important risk factor for the development of asthma in infancy and adulthood. Exposure in adulthood worsens asthma control in affected individuals.

Exposure to environmental pollutants is often associated with exacerbation of pre-existing asthma. The most common external (outdoor) pollutants are: nitrogen oxides, ozone, fine particulate matter PM10, carbon monoxide and sulfur dioxide. They increase mainly during the winter months in the cities, for the most frequent vehicular traffic, for domestic heating and for the climatic environmental conditions favorable to their concentration. Modern buildings, characterized by a reduced air exchange, can contribute to a greater exposure to chemical pollutants (irritating fumes and vapors) present in indoor (indoor) environments deriving from the combustion of gas and detergents.

Viral airway infections have also been associated with the development of asthma. If contracted in early childhood, as in the case of respiratory syncytial virus (RSV) infections, they frequently cause wheezing and bronchiolitis, which over the years become a factor favoring the development of non-allergic asthma. Viral infections in adulthood can also cause an unknown bronchial reactivity and represent the onset of asthma.

There are also some pathological conditions that can facilitate the onset of asthma or favor its exacerbations.

Nasal polyposis, rhinitis, rino-sinusitis, gastroesophageal reflux may contribute to the manifestation of asthma. The control of these diseases, therefore, also promotes the control of asthma, reducing the frequency of exacerbations.

Treatment Objective

The goal of asthma treatment is to achieve and maintain control of the clinical manifestations of the disease for prolonged periods. In other words, meet the following points: